With respect to FFXIV, where the only true progression is the MSQ, raiding is a side content even when the story is related to the MSQ. So it wouldn't make sense to consider such content to be exclusively the endgame when it's optional even as progression, as it will be bypassed as soon as a latter patch introduces better gear (or at least higher item level) from easier content.
Only two definitions of endgame would make sense for FFXIV.
1. Any content that requires level cap to do.
2. Any content that requires completion of x.0 MSQ to unlock, even if you can then do it on a job that is not max level.
So while leveling itself doesn't fit either of those, doing endgame content on another job is a valid suggestion to make in FFXIV for someone who has done the content on their main job. And it is only a suggestion, which can be rejected as a solution depending on player preference (no one should have to play a job they don't like), but not as being off topic to the thread.
Endgame is a game concept. It's the final stage of a game. The endgame to a chess game is doing similar things as in the beginning of the game, only potentially with less pieces on the board. FFXIV doesn't have to strictly follow other MMO's concept of endgame.Endgame is an MMO concept
That is fair. Again, which is why some people have said it would've been better if this thread was constructed in such a way to elicit such responses rather than complaining about a lack of content and asking whether people feel satisfied with it and how they keep busy, but only for specific content.
As for what could be done to improve, as I've said, it's difficult to say without messing with the patch cycle that the developer seems to like. I like the comparison of FFXIV that I heard on YouTube to a wide shallow pool where the enjoyment comes in at swimming across the pool rather than diving deep. FFXIV has a diverse content to partake in, but if you only enjoy a small part of it, then it can leave you feel unsatisfied unless you find a way to prolong your enjoyment of said content, like redoing it on a different job that you may like.